The present invention relates to an improved wrench and more specifically to a wrench having an improved retaining assembly for releasably mounting a worm gear on the frame of the wrench.
A known adjustable open end wrench includes a worm gear which turns on a shaft or pin that is threaded on one end. The shaft is secured into a mating thread in the head of a wrench handle and locked in position by a staking operation. This known wrench includes a coil spring which is utilized to reduce end play between the worm gear and the slot or cavity in the wrench handle.
With this known wrench, the required thread tolerances between the tapped hole in the wrench handle and the threaded shaft are critical and troublesome. Tap breakage and resulting machine down time is expensive. Coil spring interferences between the shaft, the drilled hole and the counterbore in the worm gear also contribute to the cost of manufacturing the wrench. In addition, screwing the shaft into its position in the wrench handle is slow and occasional disassembly requirements are burdensome.
Another known wrench is disclosed in U.S. Pat. No. 1,431,451. This wrench utilizes a pair of pins to mount a worm gear in a gear cavity in the wrench handle. One of the pins is disposed in a hole in a cavity in the frame of the wrench. The outer end of this pin is received in a bore in the worm gear. The pin has a larger external diameter than the bore in the worm gear and cannot be telescoped into the bore of the worm gear. A second pin, which also has a larger outside diameter than the bore in the worm gear, presses the worm gear against the first pin under the influence of a biasing spring. When the jaws of the wrench disclosed in this patent are in an open position, the worm gear can be moved axially toward the fixed jaw against the influence of the biasing spring and could result in accidental or inadvertent disassembly of the wrench. Other adjustable wrench constructions are disclosed in U.S. Pat. Nos. 1,747,360; 3,580,115 and 3,673,896.